24v Travel Trailer System

[Jracine]

Hello Everyone.

I’m looking to set up a travel trailer with a solar system. I have zero solar/inverter experience however I’ve been reading and absorbing as much information as I can on solar, ESS, and inverters and this is what I’ve come up with so far. I don’t have the travel trailer yet however I want to have a plan ironed out as this will be part of the trailer purchase budget and will be installed before departing on any trips with the trailer. I want to do it right the first time. I'm looking around 20 to 25' range.

I’m not planning on full time inverter use; I plan on living off the DC systems unless I am actively using 120VAC appliances. I’m hoping that the wealth of knowledge on this forum can poke holes in my plan and help me see things I might not have considered.

Some of the things I still have to figure out and research are:

• Energy audit, I am still shopping around for a travel trailer so I don’t know 100% what the OEM equipment will draw. 12VDC compressor fridge, propane/120vac hot water tank, propane furnace will be my largest DC draws. Other than those its lights and small device charging.

• How to deal with the 12v into the trailer from tow vehicle. I’m not interested at this time to charge my battery bank from my truck’s alternator. I guess I could remove the 12v+ from the trailer’s 7 pin connector to keep my truck’s alternator from charging the trailers battery bank, however that seems like a hassle if I need to power the trailer’s 12V systems from my truck if I run into dead batteries or any unforeseen reasons. I am wondering on how feasible it would be to use something like this switch so I can pick between the 12v from my 24-12 converter or the tow vehicle’s 12v system as required? Am I overthinking this? Will the Orion 24/12-70 even allow power to back feed? The user manual on that device is very limited.

• My plan was to leave the stock converter in place and turn off and tape the breaker to the converter to stop converter? Or just remove the AC-in for the OEM 12VDC converter.

• I don’t plan on running my trailers hot water heater or air conditioning on inverted power. If I understand the multiplus 2 operation properly if I run those loads off of AC-out2 they will only have power when connected to shore power?

I know that without having been able to actually see hourly usage on various draws that it’s pretty much an educated guess but am I way off here or am I in the right ball park? Sorry if the wiring diagram is a little difficult to follow.

 

[Solarcabin Channel]

A 12/24 volt car fridge/freezer will pull 45-50 watts when running but depending on ambient temp they only run a few minutes each hour.

Use an OD propane water heater, 12 volt shurflo pump, RV style water tank to preheat and only the pump draws power when in operation. Use a cut off switch so it doesn't back siphon and keep the pump running.

Propane heaters don't require a power supply unless you have one with a fan. Use a radiant propane heater instead of the blue flame and you really don't need a fan. I have a small USB fan on top of my radiant and takes about 10 watts to run. Much more efficient than the installed heater fans.

I would use both 12 volt and an inverter so you have more options for appliances. The smaller inverters like a 500 watt work well and sip power.

LED lights use about 10 watts. Laptop computer on the low end will use 10-25 watts unless you are gaming or watching videos.

That is basically my main cabin system and that is 400 watts solar and a 200Ah LFP battery. I use a 1200 watt inverter and MPPT controller.

That will even run a smaller microwave, vacuum, recharge an ebike and tools and lots of low power cooking appliances and gadgets. Just run them in the daytime so battery can recharge before night.

 

[Jracine]

Thank you for the reply!

I had not thought about radiant heat, are you talking about the wall mount radiant heaters? I've used those in a garage when I've had to work in there are they are quite warm, but I'm not sure how I'd go about mounting one of those and safely operate it in a travel trailer. The on-demand hot water, are they typically much more efficient?

Do you find that your 400 watts of solar are sufficient to charge up your 200AH LFP? I'm thinking of 1200 Watts but I expect to be very happy if I get 50% of that with flat rooftop mounted panels on the travel trailer, especially when the days get short.

I don't foresee myself spending a whole lot of time in the winter in the travel trailer, at least to start, and when I do I doubt I'll want to bother with any inside plumbing.

 

[chrisski]

Something to plan to is 200 ah to 400 ah of battery would be good for boondocking. If you can easily install 1200 watts, that’s be better.

My biggest draw DC is the fan blower motor for the propane heater. A colder night may drain a 200 ah bank.

My plan was to leave the stock converter in place and turn off and tape the breaker to the converter to stop converter? Or just remove the AC-in for the OEM 12VDC converter.

Turning the breaker off is easier. The converters tend to be buried behind a wall panel which would need to be removed if you pulled the plug.

Do you find that your 400 watts of solar are sufficient to charge up your 200AH LFP?

If you put in lithium, your converter might need to be swapped. Volts are different and might harm a lithium battery.

 

[Solarcabin Channel]

Thank you for the reply!

I had not thought about radiant heat, are you talking about the wall mount radiant heaters? I've used those in a garage when I've had to work in there are they are quite warm, but I'm not sure how I'd go about mounting one of those and safely operate it in a travel trailer. The on-demand hot water, are they typically much more efficient?

Do you find that your 400 watts of solar are sufficient to charge up your 200AH LFP? I'm thinking of 1200 Watts but I expect to be very happy if I get 50% of that with flat rooftop mounted panels on the travel trailer, especially when the days get short.

I don't foresee myself spending a whole lot of time in the winter in the travel trailer, at least to start, and when I do I doubt I'll want to bother with any inside plumbing.

Yes, you can get the wall mount radiant hearers like the dynaglo tat don't require a vent and burn at 99.8% efficient.

400 watts solar will recharge a 200Ah in about 10 hours of good sunlight. Unlikely you will drain your battery every day if you run most stuff in the day time and you have shore power.

 

[RoadTurtle]

If your mfg offers generator prep package, get it. My multiplus is wired to the Automatic Transfer Switch. that came as part of the prep package.

My 5th wheel is powered 24/7 on both 120v & 12v. It's awesome knowing that I can mostly live normal all off of batteries. Mostly, aircon is limited to just a few hours on battery, and I do need to run fridge and hot water on propane. The multiplus is freaking awesome with it's power sharing capability.

 

[featherlite]

I and many others would not use propane to heat a trailer or an RV on a regular basis because the units produce excessive moisture that will likely cause visible condensation in the living space and eventually cause rotted wood and mold growth.

 

[chrisski]

I and many others would not use propane to heat a trailer or an RV on a regular basis because the units produce excessive moisture that will likely cause visible condensation in the living space and eventually cause rotted wood and mold growth.

Don’t all modern propane heaters vent outside?

The exhaust is extremely moist and totally separate from the air that gets heated and sent to the cabin.

 

[Solarcabin Channel]

I and many others would not use propane to heat a trailer or an RV on a regular basis because the units produce excessive moisture that will likely cause visible condensation in the living space and eventually cause rotted wood and mold growth.

So do NG furnaces which is why they have a drip pan and are installed in a garage.

If you have high humidity go with the vented propane and condensation should not be an issue. Add some ventilation as well.

He isn't planning on using it over winter so should not be a problem.

 

[Solarcabin Channel]

Don’t all modern propane heaters vent outside?

The exhaust is extremely moist and totally separate from the air that gets heated and sent to the cabin.

You can get vented and vent free. If high humidity and condensation is a problem go with a radiant vented heater. Also have some ventilation.

 

[featherlite]

Yes, you can get the wall mount radiant hearers like the dynaglo tat don't require a vent and burn at 99.8% efficient.

I googled dyna glow radiant heaters and this came up:

https://dynagloheater.com/product/delux-50k-125k-lp-radiant-heater-ra125lpdgd/



The Dyna Glow heater appears to be non vented.

 

[Solarcabin Channel]

I googled dyna glow radiant heaters and this came up:

https://dynagloheater.com/product/delux-50k-125k-lp-radiant-heater-ra125lpdgd/

View attachment 172337

The Dyna Glow heater appears to be non vented.

Hmmm? Never saw that one before.

This is the one I have:

Dyna-Glo IR18PMDG-1 18,000 BTU Liquid Propane Infrared Vent Free Wall Heater​

On Amazon.

These heat objects in front of them instead of the air and no fan needed but I use a small DC fan on top just to move the air around better.

Good size for heating a room or cabin up to 400 sqft.

It is non vented and burns at over 99% efficiency so no vent needed. You can get vented propane heater on Amazon.

 

[Jracine]

Something to plan to is 200 ah to 400 ah of battery would be good for boondocking. If you can easily install 1200 watts, that’s be better.

My biggest draw DC is the fan blower motor for the propane heater. A colder night may drain a 200 ah bank.

Turning the breaker off is easier. The converters tend to be buried behind a wall panel which would need to be removed if you pulled the plug.

If you put in lithium, your converter might need to be swapped. Volts are different and might harm a lithium battery.

Thank you. My plan is either (2) 24V 200AH EG4 LL batteries or 2 DIY 24v banks with some 280k cells or something similar. Good to know that the blower motor may drain a 200AH battery, I was not expecting that.

My plan was to turn off the converter, battery bank charging from a SCC and the multiplus when I have shore power.

 

[Jracine]

If your mfg offers generator prep package, get it. My multiplus is wired to the Automatic Transfer Switch. that came as part of the prep package.

My 5th wheel is powered 24/7 on both 120v & 12v. It's awesome knowing that I can mostly live normal all off of batteries. Mostly, aircon is limited to just a few hours on battery, and I do need to run fridge and hot water on propane. The multiplus is freaking awesome with it's power sharing capability.

I am unlikely to have generator prep kit. When I started looking into all of this I quickly saw the benefits of the multiplus, it looks like a very nice device!

 

[chrisski]

Thank you. My plan is either (2) 24V 200AH EG4 LL batteries or 2 DIY 24v banks with some 280k cells or something similar. Good to know that the blower motor may drain a 200AH battery, I was not expecting that.

The blower motor uses 10 amps. The coldest night I was out seemed to run non-stop.

My plan was to turn off the converter, battery bank charging from a SCC and the multiplus when I have shore power.

That will work.

When hooked to shore power, I leave my converter off and continue to charge from the SCC to run my DC side off batteries and AC side off shore power. It’s usually not cold when I go to a campground, so it’s only a few hundred watts of DC I produce.

I put so much work into building it, I want to squeeze every watt possible out of it

 

[RoadTurtle]

When hooked to shore power, I leave my converter off and continue to charge from the SCC to run my DC side off batteries and AC side off shore power. It’s usually not cold when I go to a campground, so it’s only a few hundred watts of DC I produce.

I put so much work into building it, I want to squeeze every watt possible out of it

that was my plan until our long term winter site is 30a instead of 50a Complicating my configuration, as the MP II 2x is literally completely separate system from 50a hookup. 50a I'd do exactly what you're suggesting, 30a goes to the MP II for power sharing.

 

[Jracine]

Is the 12v going into the trailer from the tow vehicle a concern with regards to backfeeding though the Orion 24/12-70?

 

[Jracine]

Now I'm thinking I might be better off using a Orion 24/12-30 isolated and leave the original lead acid battery in the trailer to assist with higher in-rush load like a slide. The Orion keeping the 12v lead acid battery charged up and isolated from any back feeding while also keeping all the 12v system as is on the trailer. Does anyone have any thoughts on this?

 

[chrisski]

Have you measured the dc draw on leveling and slide outs?

Now I'm thinking I might be better off using a Orion 24/12-30 isolated and leave the original lead acid battery in the trailer to assist with higher in-rush load like a slide. The Orion keeping the 12v lead acid battery charged up and isolated from any back feeding while also keeping all the 12v system as is on the trailer. Does anyone have any thoughts on this?

My leveling jacks are 50 amps 12 v DC. I use a 24 volt to 12 volt 70 amp Victron dc to dc Orion converter.

Slide outs take less, but I’m not sure how much less.

 

[Jracine]

My leveling jacks are 50 amps 12 v DC. I use a 24 volt to 12 volt 70 amp Victron dc to dc Orion converter.

Slide outs take less, but I’m not sure how much less.

Thank you.

I don't have the trailer yet but I know the ones I'm looking at will have manual jacks but a power slide out. Looking at the component manuals for the most likely RV purchase, seems like the slides use around a 30A fuse.

How did you manage the merging of the tow vehicle 12vdc and the 24/12-70 Orion going to the 12vdc distribution?

I think the only thing I have left to figure out, unless I have overlooked a safety/wiring issue is the tow vehicle power (I'm more used to troubleshooting from a wiring diagram, not drawing them up haha). I think my 3 options are as follows:

1. Remove the OEM battery, use the 24/12-70 to power 12v loads, block the 12v charge from the tow vehicle.
2. Keep the OEM battery, use it as a buffer for momentary large loads and keep it charged with a Orion smart 24/12-30 isolated DC-DC keeping the 12V in from the tow vehicle.
3. Keep the OEM battery, use the 24/12-70 to power loads/keep battery charged and use a 3 position switch to keep the non isolated orion from the tow vehicle's 12vdc.

I think option 2 is probably the best as it is more "plug and play" and offers some redundancy for 12v power.

Thank you everyone for the help!